The space debris population in low Earth orbits (LEO) has been extensively studied during the last decade and reasonable models covering all size ranges were produced. Information on the distribution of objects in the geostationary ring (GEO), however, is still comparatively sparse. Until quite recently the population of man-made objects in GEO had

We report the discovery of two new ZZ Ceti pulsators, LP 133-144 and HE 1258+0123, selected on the basis of model atmosphere fits to optical spectroscopic data. The atmospheric parameters for LP 133-144 (Teff=11,800+/-200 K and logg=7.87+/-0.05) and for HE 1258+0123 (Teff=11,410+/-200 K and logg=8.04+/-0.05) place them within the empirical

Using available optical and X-ray catalogues of clusters and superclusters of galaxies, we build templates of thermal Sunyaev-Zel'dovich (tSZ) emission as they should be detected by the WMAP experiment. We compute the cross-correlation of our templates with WMAP temperature maps, and interpret our results separately for clusters and for

We have conducted a detailed study of the open clusters NGC 2451 A and B which are located along the same line of sight at 206pc and 370pc distance respectively. Although belonging to the nearest clusters they have not been much investigated until present due to strong contamination by field stars. ROSAT X-ray observations and optical UBVR

We present a photometric survey of bright southern stars carried out using the DENIS instrument equipped with attenuating filters. The observations were carried out not using the survey mode of DENIS, but with individual target pointings. This project was stimulated by the need to obtain near-infrared photometry of stars to be used in early

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